Layer blocking the stairs?

Hi everyone,
I’m new to creating Fortnite maps, and to get started I wanted to make a TWDU map using the available template. However, I’m running into a problem: it seems like a layer is blocking the stairwell.
Does anyone know how to fix this? Thanks in advance!

A few things,

Did you place any blocking volumes down? Also, as a test, try starting a new template island and see if you get the same thing.

Let me know!